A prior printing apparatus performs desired printing on a medium, such as recording paper. The printing apparatus prints by ejecting ink from an ink head that is moved in a direction perpendicular to a transfer direction of the medium. Such a printing apparatus may be provided with a plurality of transfer mechanisms, each including drive rollers and pinch rollers formed over a platen that extends in the moving direction of the ink head, and linearly arranged at predetermined intervals.
The drive rollers forming the transfer mechanism are each rotated by a drive motor, and the pinch rollers are brought into elastic contact with the drive rollers. A medium that is held between the drive rollers and the pinch rollers is transferred by the rotation of the drive rollers in the transfer direction.
Notably, the printing apparatus equipped with the transfer mechanism having the structure described above is susceptible to problems. For example, unless the medium is set correctly with respect to the transfer direction, wrinkles form on the medium and jamming of the medium in the printing apparatus occurs. Hence, if the medium is skewed at the time of setting the medium in the printing apparatus, the medium must be removed from, and reset at, the transfer mechanism. Accordingly, the prior printing apparatus is problematic due to the complication involved with setting the medium in the transfer mechanism.
In a previous attempt to solve the problems of the prior printing apparatus, a printing apparatus has been provided wherein all pinch rollers in respective transfer mechanisms can be moved up and down at the same time. Each of the transfer mechanisms includes a pinch roller lever that is rotatable about a supporting shaft. A pinch roller is provided at a front end of the pinch roller lever, and a shaft is provided at a rear section of the pinch roller lever. The shaft, as it is rotated, pushes the rear section of the pinch roller lever, thereby raising the front end of the pinch roller lever.
The shafts for the respective transfer mechanisms each have a rectangular or oval cross-sectional shape, and are formed as one piece. When the shaft is rotated, the pinch roller is raised or brought down at each of the transfer mechanisms. When an operator rotates the shaft as necessary, the shaft pushes the rear section of the pinch roller lever, thereby raising a front tip of the pinch roller lever and raising the pinch roller such that an elastic contact state between the pinch roller and drive roller is released.
Accordingly, when the orientation of the medium is to be corrected at the time of setting the medium, the shaft is rotated to raise the pinch rollers, and the orientation of the medium is corrected. Thereafter, the shaft is rotated again to lower the pinch rollers, whereby the medium can be held between the drive rollers and the pinch rollers in a proper state.
However, according to the previously-described printing apparatus, the pinch rollers are raised or lowered by the operator. If the operator does not have the requisite experience to operate the printing apparatus, the operation of raising and lowering the pinch rollers cannot be performed properly. Consequently, if the orientation of the medium is corrected in a state in which the pinch rollers are not raised, problematic wrinkles and creases are formed on the medium.
Meanwhile, when the medium is a piece of cloth, the transfer of the medium at the time of media transfer becomes unstable if the drive rollers and pinch rollers pinch loose threads at an end of the piece of cloth. In this case, the previously-described printing apparatus is not useful because all pinch rollers are raised or lowered at the same time. Hence, with the previously-described printing apparatus, it is not possible to raise only a portion of the pinch rollers that are located at the end of the piece of cloth which pinch the loose threads.
Accordingly, what is needed is a printing apparatus to solve the various problems of the prior art described above, the object of which is to provide a pinch roller lifting mechanism that is capable of selecting pinch rollers to be raised or lowered, and facilitating the operation of raising and lowering the pinch rollers.